Exercise training-induced extracellular miR-136-3p modulates glucose uptake and myogenesis through targeting of NRDC in human skeletal muscle.

Abstract

BACKGROUND Regular physical training induces adaptive effects across multiple organ systems, highlighting the existence of inter-organ communication networks. However, the molecular mechanisms underlying both exercise-induced adaptations and organ-to-organ signaling are not fully characterized. Circulating extracellular vesicles (EVs), including exosomes, carry molecules like microRNAs (miRNAs) that may mediate tissue crosstalk. This study aimed to identify specific exercise training-responsive miRNAs that affect skeletal muscle function. METHODS miRNA expression profiles of serum-derived EVs were analyzed in healthy young individuals before and after 3 weeks endurance exercise training. Exercise training-responsive miRNAs were then validated for a functional role in cellular metabolic processes in human myotubes. RESULTS We identified several exercise training-responsive miRNAs within exosome-rich EVs in serum, including miR-136-3p. In human myotubes, miR-136-3p enhanced glucose uptake and targeted the nardilysin convertase (NRDC) gene. Transfection of miR-136-3p or silencing of NRDC induced a shift towards glycolytic metabolism in mitochondria and modulated gene expressions related to myogenesis. Pancreatic islets were identified as a potential source of miR-136-3p based on in silico analysis of gene expression and a molecular analysis of conditioned media from isolated pancreatic islets. CONCLUSION MiR-136-3p is an endurance training-responsive molecular transducer that modulates glucose metabolism and cellular proliferation in myocytes. Associated with EVs, extracellular miR-136-3p may serve as a molecular messenger to communicate islet-skeletal muscle crosstalk after exercise. Extracellular miR-136-3p may serve as a molecular messenger to communicate islet-skeletal muscle crosstalk. Our results highlight a miRNA-mediated mechanism that participates in inter-organ communication to fine tune the metabolic adaptations to exercise.